1. Which process involves the body's natural defense against inhaled dust and allergens?

A. Cellular respiration
B. Gas exchange
C. Ciliary action
D. Bronchoconstriction

Correct answer: C

Rationale: The correct answer is C: Ciliary action. Cilia are tiny hair-like structures lining the respiratory tract that help trap and remove inhaled dust and allergens. When these particles are trapped in the mucus produced by the cilia, the cilia beat in a coordinated fashion to move the mucus and its trapped particles out of the respiratory system, preventing them from reaching the lungs. Cellular respiration (A) is the process by which cells generate energy from nutrients, not a defense mechanism. Gas exchange (B) refers to the exchange of oxygen and carbon dioxide in the lungs, not a defense mechanism. Bronchoconstriction (D) is the narrowing of the airways, often in response to triggers like allergens, but it is not the body's natural defense mechanism against inhaled dust and allergens.

2. Which of the following is the main organ responsible for regulating sleep?

A. Thalamus
B. Hypothalamus
C. Pituitary gland
D. Pineal gland

Correct answer: B

Rationale: Rationale: The hypothalamus is the main organ responsible for regulating sleep. It plays a crucial role in controlling the body's circadian rhythm, which is the internal clock that regulates the sleep-wake cycle. The hypothalamus receives input from the eyes about light and darkness, which helps in determining when it is time to sleep or wake up. It also regulates the production of melatonin by the pineal gland, which is a hormone that helps control sleep patterns. While the thalamus is involved in relaying sensory information to the brain, the pituitary gland is responsible for producing and releasing hormones, and the pineal gland produces melatonin under the control of the hypothalamus.

3. Which element is a critical component of DNA and RNA, essential for storing and transmitting genetic information?

A. Oxygen
B. Carbon
C. Nitrogen
D. Hydrogen

Correct answer: B

Rationale: Carbon's ability to form diverse bonds makes it the backbone of genetic molecules, enabling efficient information storage and transmission

4. What is the function of ribosomal RNA (rRNA)?

A. Carries amino acids to the ribosomes
B. Reads th(a) Carries amino acids to the ribosomes: This is the function of transfer RNA (tRNA), not ribosomal RNA. (b) Reads the genetic code on mRNA: This is the function of the ribosomes as a whole, not just the ribosomal RNA. (d) Controls the rate of protein synthesis: This is a more complex process involving various factors, not solely ribosomal RNA. e genetic code on mRNA
C. Forms the structural framework of ribosomes
D. Controls the rate of protein synthesis

Correct answer: C

Rationale: Rationale: Ribosomal RNA (rRNA) plays a crucial role in forming the structural framework of ribosomes, which are the cellular organelles responsible for protein synthesis. Ribosomes consist of both protein and rRNA components, with rRNA providing the structural support necessary for the ribosome to function properly. This structural framework allows the ribosome to interact with messenger RNA (mRNA) and transfer RNA (tRNA) during the process of translation, where the genetic information encoded in mRNA is used to assemble proteins from amino acids. Therefore, the primary function of rRNA is to contribute to the structure and function of ribosomes, rather than directly carrying amino acids, reading the genetic code, or controlling the rate of protein synthesis.

5. The constituents of an atomic nucleus consist of:

A. Electrons and protons only
B. Protons and neutrons only
C. Electrons, protons, and neutrons
D. None of the above

Correct answer: B

Rationale: The correct answer is B: "Protons and neutrons only." This is because the atomic nucleus is composed of protons, which carry a positive charge, and neutrons, which are neutral. Electrons are found outside the nucleus in electron shells. Protons and neutrons are collectively known as nucleons and are responsible for the mass of the atom. Electrons are much lighter and are involved in chemical reactions and bonding. Therefore, the constituents of an atomic nucleus are specifically protons and neutrons, making option B the correct choice.

6. Which of the following is NOT a primary producer in an ecosystem?

A. Grass
B. Deer
C. Algae
D. Mushroom

Correct answer: B

Rationale: Rationale: - A) Grass: Grass is a primary producer because it can photosynthesize and convert sunlight into energy, making it the base of the food chain. - B) Deer: Deer are consumers that feed on primary producers like grass, so they are not primary producers themselves. - C) Algae: Algae are primary producers that can photosynthesize and produce energy from sunlight. - D) Mushroom: Mushrooms are decomposers that break down organic matter, so they are not primary producers.